Sio2, which melts at 1723°c, and tio,, which melts at 1842°c, in the solid state, and the sio,-tio, binary system contains a monotectic equi- librium at 1794°c, at which temperature virtually pure tio, is in equilibrium with two liquids containing mole fractions of sio, of 0.04 and 0.76. if, for the purpose of simple calculation, it is assumed that the compositions of the two liq- uids are immiscible are xsio 0.24 and xsio, 0.76 and that the liquid solutions are regular in their behavior, what is the value of a, and at what temperature does the liquid toaibilitu aan disannear?